1. Field of the Invention
The present invention relates generally to a peroxidation process for producing peroxides from organic compounds, such as production of alkyl peroxides and/or alkyl aryl peroxides from alkanes and/or alkyl aryl compounds and oxygen. More specifically, this invention relates to production of such peroxides in a reactor in which liquid product streams are withdrawn from locations near the top and bottom of the reactor. In particular, this invention relates to a process for the non-catalytic or auto-catalytic production of tertiary butyl hydroperoxide ("TBHP") and tertiary butyl alcohol ("TBA") from isobutane and oxygen in a vertical reactor in which a first liquid product stream is typically withdrawn from a position adjacent the top of the reactor and a second liquid product stream is typically withdrawn from a position adjacent the bottom of the reactor.
2. Description of Related Art
The non-catalytic or auto-catalytic liquid phase reaction of organic compounds, such as alkanes or alkyl aryl compounds, with molecular oxygen to produce peroxides is commonly performed in reactor vessels. By "auto-catalytic reaction" it is meant that no catalyst is required, either continuously or in a fixed bed. Such peroxidation reaction processes include, for example, peroxidation processes such as those described in U.S. Pat. No. 5,436,375. For example, a vertical or horizontal reactor vessel may be configured to receive a liquid alkane feed through which molecular oxygen is bubbled under reaction conditions to form, for example, alkyl peroxides and/or alcohols. Typically, such reactors are configured with one or more internal weirs for maintaining one or more reactant liquid levels through which molecular oxygen may be bubbled for reaction. Alkyl peroxide and/or alcohol-containing product streams are typically recovered from liquid which overflows the weir. In this regard, one or more weirs may be utilized to maintain a single alkane liquid level within a reactor vessel, or may be configured to maintain sequentially decreasing levels (such as by separating multiple compartments in a horizontal reactor vessel) through which a liquid reactant phase moves by overflowing each sequential weir. In the latter case, oxygen may be injected into each compartment between the weirs.
In peroxidation reactors, compounds such as alkyl peroxides, alkyl aryl peroxides and/or alcohols are typically prepared by sparging oxygen or a mixture of liquid and/or gaseous alkane and/or alkyl aryl with oxygen to the bottom of the reactor and by charging a feed stream of fresh and/or recycled liquid alkane and/or alkyl aryl compound to the top of the reactor, and by withdrawing a liquid weir overflow product stream from a point adjacent the top of the reactor and a vapor product stream from the top of the reactor. For example, in one typical process for the non-catalytic or auto-catalytic production of TBHP and TBA from isobutane and oxygen, a vertical reactor is employed. In this process TBHP and TBA are produced from isobutane and oxygen by sparging a mixture of isobutane with oxygen to the bottom of the reactor, by charging a reaction mixture recycle stream to the reactor above the sparge point, by centrally charging a downwardly flowing stream of cooled isobutane (fresh isobutane, recycled isobutane, or a mixture thereof) to the top of the reactor to induce central downflow of the isobutane and annular upflow of the sparged mixture in the recycle stream, by withdrawing a liquid product stream adjacent the top of the reactor, by withdrawing a vapor product stream from the top of the reactor, by condensing liquids from the vapor product, and by recycling the condensed liquids and recovering the liquid product stream.
In liquid phase peroxidation reactors such as those described above, productivity of peroxide, such as TBHP may suffer over time. With a reduction in peroxide productivity may also come an increase in alcohol (e.g., TBA) production. At the same time, acid number and presence of undesirable byproducts in the liquid product stream typically increases. Such undesirable by-products include methanol, acetone, and other compounds easily oxidized to acid compounds. Other related phenomena may include increased production of carbon monoxide and carbon dioxide which, among other things, may lead to increased pressure in a reactor vessel and which may in turn necessitate reduction in rates due to pressure concerns in the reactor and downstream of the reactor vessel. Therefore, in conventional peroxidation reaction processes, productivity of peroxide may be reduced due to decreased selectivity to peroxide coupled with a reduction in flow rates in order to maintain reactor pressure at an acceptable level. In this regard, design pressure limits are typically dictated by economics and/or construction parameters.